National Democrats Investing in Ariz. Senate Race

National Democrats are boosting their investment in Arizona's Senate race to replace retiring Sen. Jon Kyl, another sign that the race between Republican Jeff Flake and Democrat Richard Carmona is competitive.

The Democratic Senatorial Campaign Committee says it is purchasing $526,000 in air time over the coming six days in Arizona. That comes on top of about $500,000 the committee has already dedicated to the race.

Federal Election Commission records indicate that a super PAC affiliated with the tea party movement, Freedom Works for America, has also started to weigh into the race. It's spent more than $200,000 over the past two weeks on signs, online ads and other activities designed to help Flake.

Republicans have a distinct advantage in Arizona with no Democrat holding statewide office.